In general, it is desirable that a charging current and a charging voltage for a rechargeable battery be controlled at the time of charging so as to obtain an appropriate charging pattern (charging profile) in accordance with the type of the rechargeable battery, for example, a lithium-ion battery, a nickel-cadmium battery, an electric double layer capacitor, or a nickel-hydrogen battery. Examples of appropriate charging patterns corresponding to battery types are illustrated in FIGS. 1A and 1B. For example, in the case of lithium-ion batteries, it is desirable to perform constant-current charging and then perform constant-voltage charging after a charging voltage has reached a predetermined value. For example, in the case of nickel-hydrogen rechargeable batteries, it is desirable to perform constant-current charging and to terminate the charging when voltage drop or temperature rise occurs.
In order to achieve such an appropriate charging pattern, a charging control circuit may be connected to a rechargeable battery. When a charging control circuit is connected to only a single type of rechargeable battery, an appropriate charging pattern can be easily achieved. In contrast, when a rechargeable battery is exchangeable, an unsupported type of rechargeable battery may be connected to a charging control circuit and the rechargeable battery may be charged in accordance with an inappropriate charging pattern. A charging control circuit capable of identifying the type of a rechargeable battery and charging only a supported type of rechargeable battery is sometimes used. See, for example, Japanese Unexamined Patent Application Publication No. 2001-266955 (Patent Document 1).
In order to connect a rechargeable battery disposed in a power receiving terminal such as an RFID, a wireless handset, or an electric shaver to mains, non-contact power transmission using a near-electromagnetic field, that is, non-contact charging requiring no power line between the power receiving terminal and mains, is sometimes performed. In this case, a charging control circuit is disposed in the power receiving terminal. The power receiving terminal sometimes transmits a signal to a power transmission terminal by performing load modulation communication so as to be authenticated. See, for example, Japanese Unexamined Patent Application Publication No. 2003-23366 (Patent Document 2).